Method of processing substate, method of manufacturing semiconductor device, substrate processing apparatus, and recording medium

ABSTRACT

There is provided technique including: forming film on substrate by performing cycle, predetermined number of times, including non-simultaneously performing: (a) supplying precursor gas and inert gas to the substrate; and (b) supplying reaction gas to the substrate, wherein in (a), at least one selected from the group of the precursor gas and the inert gas stored in first tank is supplied to the substrate, and at least one selected from the group of the precursor gas and the inert gas stored in second tank is supplied to the substrate, and concentration of the precursor gas in the first tank while at least one selected from the group of the precursor gas and the inert gas is stored in the first tank differs from that in the second tank while at least one selected from the group of the precursor gas and the inert gas is stored in the second tank.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2019-093761, filed on May 17, 2019, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a method of manufacturing a semiconductor device, a substrate processing apparatus, and a recording medium.

BACKGROUND

In the related art, as one step in a process of manufacturing a semiconductor device, a step of forming a film such as a nitride film on a substrate by alternately supplying a precursor gas and a reaction gas to the substrate may be carried out.

SUMMARY

Some embodiments of the present disclosure provide a technique capable of improving uniformity of substrate in-plane film thickness of a film formed on a substrate.

According to an embodiment of the present disclosure, there is provided a technique that includes: forming a film on a substrate in a process chamber by performing a cycle a predetermined number of times, the cycle including non-simultaneously performing: (a) supplying a precursor gas and an inert gas to the substrate; and (b) supplying a reaction gas to the substrate, wherein in (a), at least one selected from the group of the precursor gas and the inert gas stored in a first tank is supplied to the substrate from a first supplier, and at least one selected from the group of the precursor gas and the inert gas stored in a second tank different from the first tank is supplied to the substrate from a second supplier different from the first supplier, and wherein a concentration of the precursor gas in the first tank in a state where at least one selected from the group of the precursor gas and the inert gas is stored in the first tank is set to be different from a concentration of the precursor gas in the second tank in a state where at least one selected from the group of the precursor gas and the inert gas is stored in the second tank.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic configuration view of a vertical process furnace of a substrate processing apparatus suitably used in an embodiment of the present disclosure, in which a portion of the process furnace is shown in a vertical sectional view.

FIG. 2 is a schematic configuration view of a vertical process furnace of a substrate processing apparatus suitably used in an embodiment of the present disclosure, in which a portion of the process furnace is shown in a cross section taken along line A-A.

FIG. 3 is a schematic configuration view of a controller of a substrate processing apparatus suitably used in an embodiment of the present disclosure, in which a control system of the controller is shown in a block diagram.

FIG. 4 is a diagram showing an example of supply timings of main gases and supply timings of RF power in a film-forming sequence according to an embodiment of the present disclosure.

FIG. 5 is a diagram showing another example of supply timings of the main gases and supply timings of the RF power in the film-forming sequence according to the embodiment of the present disclosure.

FIG. 6 is a diagram showing an example of supply timings of main gases and supply timings of RF power in a film-forming sequence according to another embodiment of the present disclosure.

FIG. 7 is a table showing measurement results of uniformity of wafer in-plane film thickness and uniformity of inter-wafer film thickness when a SiN film is formed on a wafer while changing conditions of gas charging into a tank.

FIG. 8 is a bar graph showing measurement results of a wet etching rate of a SiN film when the SiN film is formed on a wafer while changing conditions of gas charging into a tank.

FIG. 9 is a table showing measurement results of an effective flow rate of a dichlorosilane gas and a flow rate of diluted N₂ gas necessary to comply with a standard of explosion limit of the dichlorosilane gas when a SiN film is formed on a wafer while changing conditions of gas charging into a tank.

FIG. 10 is a table showing measurement results of a wet etching rate of a SiN film when the SiN film is formed on a wafer while changing conditions of NH₃ gas supply.

DETAILED DESCRIPTION An Embodiment of the Present Disclosure (1) Configuration of Substrate Processing Apparatus

As shown in FIG. 1 , a process furnace 202 includes a heater 207 as a heating part (heating mechanism). The heater 207 has a cylindrical shape and is supported by a heater base (not shown) as a support plate so as to be vertically installed. The heater 207 also functions as an activation mechanism (an excitation part or an exciter) configured to activate (excite) a gas with heat. In the present disclosure, the term “gas” may refer to gas without liquid or gas that partially includes liquid in a mist state.

A reaction tube 203 that constitutes a reaction container (a processing container) is disposed inside the heater 207 to be concentric with the heater 207. The reaction tube 203 is made of a heat resistant material such as quartz (SiO₂) or silicon carbide (SiC) and is formed in a cylindrical shape with its upper end closed and its lower end opened. A process chamber 201 is formed in a cylindrical hollow portion of the reaction tube 203. The process chamber 201 is configured to be capable of accommodating wafers 200 as substrates. The wafers 200 processed in the process chamber 201.

In the process chamber 201, nozzles 233 a, 233 b, 233 c and 233 d as gas supply parts (or gas suppliers) are respectively installed so as to penetrate a lower side wall of the reaction tube 203. Each of the nozzles 233 a, 233 b, 233 c and 233 d is made of a heat resistant material such as quartz or SiC and is formed as an L-shaped long nozzle. Gas supply pipes 232 a 1, 232 b 1, 232 c 1 and 232 d 1 are connected to the nozzles 233 a, 233 b, 233 c and 233 d, respectively. In this manner, four nozzles 233 a, 233 b, 233 c and 233 d and four gas supply pipes 232 a 1, 232 b 1, 232 c 1 and 232 d 1 are respectively installed at the reaction tube 203, so that it is configured such that a plurality of types of gases, here, two types of gases, can be supplied into the process chamber 201. The nozzles 233 a to 233 d are also referred to as first to fourth nozzles, respectively. The gas supply pipes 232 a 1 to 232 d 1 are also referred to as first to fourth gas supply pipes (R1 to R4), respectively. The gas supply pipes 232 a 1 to 232 d 1 and a gas supply pipe to be described later are each made of a metal material such as stainless steel (SUS).

In addition, a metal manifold that supports the reaction tube 203 may be installed below the reaction tube 203, and each nozzle may be installed to penetrate the side wall of the manifold. Further, an exhaust pipe 231 to be described later may be installed at the manifold. In this case, the processing container (reaction container) is constituted by the reaction tube 203 and the manifold. In this manner, a furnace port of the process furnace 202 may be made of metal, and a nozzle or the like may be attached to the metal furnace port. The manifold may be made of, for example, a metal material such as SUS.

Mass flow controllers (MFCs) 241 a 1 and 241 b 1, which are flow rate controllers (flow control parts), valves 243 a 1 and 243 b 1, which are opening/closing valves, valves 243 a 4 and 243 b 4, tanks 242 a 1 and 242 b 1, which are gas storage parts, and valves 243 a 5 and 243 b 5 are installed at the gas supply pipes 232 a 1 and 232 b 1, respectively in order from the upstream side of gas flow. Gas supply pipes 232 a 2 and 232 b 2 are connected to the gas supply pipes 232 a 1 and 232 b 1 at the downstream side of the valves 243 a 1 and 243 b 1 and at the upstream side of the valves 243 a 4 and 243 b 4, respectively. At the gas supply pipes 232 a 2 and 232 b 2, MFCs 241 a 2 and 241 b 2 and valves 243 a 2 and 243 b 2 are installed respectively, in order from the upstream side of gas flow. Gas supply pipes 232 a 3 and 232 b 3 are connected to the gas supply pipes 232 a 1 and 232 b 1 at the downstream side of the valves 243 a 5 and 243 b 5, respectively. MFCs 241 a 3 and 241 b 3, valves 243 a 3 and 243 b 3 and valves 243 a 6 and 243 b 6 are installed at the gas supply pipes 232 a 3 and 232 b 3 respectively, in order from the upstream side of gas flow. The tanks 242 a 1 and 242 b 1 are also referred to as a first tank and a second tank, respectively.

At the gas supply pipes 232 c 1 and 232 d 1, MFCs 241 c 1 and 241 d 1, valves 243 c 1 and 243 d 1 and valves 243 c 3 and 243 d 3 are installed respectively, in order from the upstream side of gas flow. Gas supply pipes 232 c 2 and 232 d 2 are connected to the gas supply pipes 232 c 1 and 232 d 1 at the downstream side of the valves 243 c 3 and 243 d 3, respectively. At the gas supply pipes 232 c 2 and 232 d 2, MFCs 241 c 2 and 241 d 2, valves 243 c 2 and 243 d 2 and valves 243 c 4 and 243 d 4 are installed respectively, in order from the upstream side of gas flow.

As shown in FIG. 2 , the nozzles 233 a, 233 b, 233 c and 233 d connected to tips of gas supply pipes 232 a 1, 232 b 1, 232 c 1 and 232 d 1 are installed in an annular space (in a plane view) between an inner wall of the reaction tube 203 and the wafers 200 so as to extend upward along an arrangement direction of the wafers 200 from a lower portion of the inner wall of the reaction tube 203 to an upper portion thereof. That is, the nozzles 233 a, 233 b, 233 c and 233 d are installed in a region horizontally surrounding a wafer arrangement region (in which the wafers 200 are arranged) at a lateral side of the wafer arrangement region, along the wafer arrangement region. Gas supply holes 248 a, 248 b, 248 c and 248 d configured to supply gases are formed on side surfaces of the nozzles 233 a, 233 b, 233 c and 233 d, respectively. Each of the gas supply holes 248 a and 248 b is opened toward the center of the reaction tube 203 and is capable of supplying the gas toward the wafers 200. The gas supply holes 248 c and 248 d are respectively opened toward centers of buffer chambers 237 c and 237 d to be described later. A plurality of gas supply holes 248 a, 248 b, 248 c and 248 d may be formed from a lower portion of the reaction tube 203 to an upper portion thereof.

The nozzles 233 a and 233 b are arranged adjacent to each other as shown in FIG. 2 . Specifically, the nozzles 233 a and 233 b are arranged at positions where a central angle θ formed between a straight line (first straight line) connecting a center of the wafer 200 and a center of the nozzle 233 a and a straight line (second straight line) connecting the center of the wafer 200 and a center of the nozzle 233 b (a central angle θ with respect to an arc with the centers of the nozzles 233 a and 233 b as both ends) is an acute angle, for example, an angle in a range of 10 to 30 degrees, specifically 10 to 20 degrees in some embodiments, when seen in the plane view.

The nozzles 233 c and 233 d are installed in the buffer chambers 237 c and 237 d, respectively, which are gas dispersion spaces. The buffer chambers 237 c and 237 d are formed between the inner wall of the reaction tube 203 and a partition 237 c 1 and between the inner wall of the reaction tube 203 and a partition 237 d 1, respectively. The buffer chambers 237 c and 237 d (the partitions 237 c 1 and 237 d 1) are respectively disposed in an annular space (in the plane view) between the inner wall of the reaction tube 203 and the wafers 200 and at a portion extending from a lower portion of the inner wall of the reaction tube 203 to an upper portion thereof along the arrangement direction of the wafers 200. That is, the buffer chambers 237 c and 237 d (the partitions 237 c 1 and 237 d 1) are respectively installed in the region horizontally surrounding the wafer arrangement region at the lateral side of the wafer arrangement region, along the wafer arrangement region. Gas supply holes 250 c and 250 d configured to supply gases are formed at ends of the surfaces of the partition 237 c 1 and 237 d 1 facing (adjacent to) the wafers 200, respectively. The gas supply holes 250 c and 250 d are opened toward the center of the reaction tube 203 and is capable of supplying the gases toward the wafers 200. A plurality of gas supply holes 250 c and 250 d are formed from the lower portion of the reaction tube 203 to the upper portion thereof.

As shown in FIG. 2 , the buffer chambers 237 c and 237 d are arranged in a line-symmetrical relationship, with having a straight line connecting the center of the wafer 200 and a center of an exhaust port 231 a (to be described later) installed at the side wall of the reaction tube 203 as a symmetrical axis when seen in the plane view. That is, the buffer chambers 237 c and 237 d are arranged such that straight lines respectively connecting the centers of the gas supply hole 250 c of the buffer chamber 237 c, the gas supply hole 250 d of the buffer chamber 237 d, and the exhaust port 231 a form an isosceles triangle. As a result, gas flows flowing from the buffer chambers 237 c and 237 d to the wafers 200 become uniform. That is, the gas flows flowing from the two buffer chambers 237 c and 237 d to the wafers 200 are line-symmetrical to each other, with having a straight line connecting the center of the wafer 200 and the center of the exhaust port 231 a as a symmetrical axis. The buffer chambers 237 c and 237 d are also referred to as a first buffer chamber and a second buffer chamber, respectively.

A halosilane-based gas containing silicon (Si) as a main element (a predetermined element) constituting a film to be formed and a halogen element as precursor gases which are film-forming gases (processing gases) can be supplied from the gas supply pipes 232 a 1 and 232 b 1 into the process chamber 201 via the MFCs 241 a 1 and 241 b 1, the valves 243 a 1 and 243 b 1, the valves 243 a 4 and 243 b 4, the tanks 242 a 1 and 242 b 1, the valves 243 a 5 and 243 b 5 and the nozzles 233 a and 233 b, respectively. The precursor gas refers to a gaseous precursor, for example, a gas obtained by vaporizing a precursor in a liquid state at normal temperature and normal pressure, a precursor in a gaseous state at normal temperature and normal pressure, and the like. The halogen element includes chlorine (Cl), fluorine (F), bromine (Br), iodine (I) and the like. The halosilane-based gas acts as a Si source. As the halosilane-based gas, for example, a chlorosilane-based gas containing Cl can be used. As the chlorosilane-based gas, for example, a dichlorosilane (SiH₂Cl₂, abbreviation: DCS) gas can be used.

A nitrogen (N₂) gas as an inert gas can be supplied from the gas supply pipes 232 a 2 and 232 b 2 into the process chamber 201 via the MFCs 241 a 2 and 241 b 2, the valves 243 a 2 and 243 b 2, the gas supply pipes 232 a 1 and 232 b 1, the valves 243 a 4 and 243 b 4, the tanks 242 a 1 and 242 b 1, the valves 243 a 5 and 243 b 5 and the nozzles 233 a and 233 b, respectively. The N₂ gas acts as a purge gas, a dilution gas, a carrier gas or a multiple adsorption suppress gas of a DCS gas.

An N₂ gas as an inert gas can be supplied from the gas supply pipes 232 a 3 and 232 b 3 into the process chamber 201 via the MFCs 241 a 3 and 241 b 3, the valves 243 a 3 and 243 b 3, the valves 243 a 6 and 243 b 6, the gas supply pipes 232 a 1 and 232 b 1 and the nozzles 233 a and 233 b, respectively. The N₂ gas acts as a purge gas, a dilution gas or a carrier gas.

A nitrogen (N)-containing gas as a reaction gas, which is a film-forming gas (a processing gas), can be supplied from the gas supply pipes 232 c 1 and 232 d 1 into the process chamber 201 via the MFCs 241 c 1 and 241 d 1, the valves 243 c 1 and 243 d 1, the valves 243 c 3 and 243 d 3, the nozzles 233 c and 233 d and the buffer chambers 237 c and 237 d, respectively. As the N-containing gas, for example, a hydrogen-nitride-based gas can be used. The hydrogen-nitride-based gas can be said to be a substance composed of only two elements, N and hydrogen (H), and acts as a nitriding gas, that is, an N source. As the hydrogen-nitride-based gas, for example, an ammonia (NH₃) gas can be used.

An N₂ gas as an inert gas can be supplied from the gas supply pipes 232 c 2 and 232 d 2 into the process chamber 201 via the MFCs 241 c 2 and 241 d 2, the valves 243 c 2 and 243 d 2, the valves 243 c 4 and 243 d 4, the gas supply pipes 232 c 1 and 232 d 1 and the nozzles 233 c and 233 d, respectively. The N₂ gas acts as a purge gas, a dilution gas or a carrier gas.

A first supply system (precursor gas/inert gas supply system) configured to supply at least one selected from the group of the DCS gas and the N₂ gas stored in the tank 242 a 1 from the nozzle 233 a to the wafers 200 in the process chamber 201 mainly includes the gas supply pipes 232 a 1 to 232 a 3, the MFCs 241 a 1 to 241 a 3, the valves 243 a 1 to 243 a 6, the tank 242 a 1 and the nozzle 233 a.

A second supply system (precursor gas/inert gas supply system) configured to supply at least one selected from the group of the DCS gas and the N₂ gas stored in the tank 242 b 1 from the nozzle 233 b to the wafers 200 in the process chamber 201 mainly includes the gas supply pipes 232 b 1 to 232 b 3, the MFCs 241 b 1 to 241 b 3, the valves 243 b 1 to 243 b 6, the tank 242 b 1 and the nozzle 233 b.

A third supply system (reaction gas/inert gas supply system) configured to supply at least one selected from the group of the NH₃ gas and the N₂ gas from the nozzle 233 c and the buffer chamber 237 c to the wafers 200 in the process chamber 201 mainly includes the gas supply pipes 232 c 1 and 232 c 2, the MFCs 241 c 1 and 241 c 2, the valves 243 c 1 to 243 c 4, the nozzle 233 c and the buffer chamber 237 c.

A fourth supply system (reaction gas/inert gas supply system) configured to supply at least one selected from the group of the NH₃ gas and the N₂ gas from the nozzle 233 d and the buffer chamber 237 d to the wafers 200 in the process chamber 201 mainly includes the gas supply pipes 232 d 1 and 232 d 2, the MFCs 241 d 1 and 241 d 2, the valves 243 d 1 to 243 d 4, the nozzle 233 d and the buffer chamber 237 d. In the present disclosure, the fourth supply system may be included in the third supply system.

As shown in FIG. 2 , two rod-shaped electrodes 269 c and 270 c made of a conductor and having an elongated structure are respectively installed in the buffer chamber 237 c along the upper portion of the inner wall of the reaction tube 203 from the lower portion thereof so as to extend upward in the arrangement direction of the wafers 200. Each of the rod-shaped electrodes 269 c and 270 c is installed in parallel with the nozzle 233 c. Each of the rod-shaped electrodes 269 c and 270 c is protected by being covered by an electrode protection tube 275 c from below to above. One of the rod-shaped electrodes 269 c and 270 c is connected to a high frequency power supply 273 via a matching device 272, and the other is connected to a ground which is a reference potential. Here, the rod-shaped electrode 269 c is connected to the high frequency power supply 273 via the matching device 272, and the rod-shaped electrode 270 c is connected to the ground which is the reference potential. By applying high frequency (RF) power between the rod-shaped electrodes 269 c and 270 c from the high frequency power supply 273 via the matching device 272, plasma is generated in a plasma generation region 224 c between the rod-shaped electrodes 269 c and 270 c.

Similarly, as shown in FIG. 2 , two rod-shaped electrodes 269 d and 270 d made of a conductor and having an elongated structure are installed in the buffer chamber 237 d along the upper portion of the inner wall of the reaction tube 203 from the lower portion thereof so as to extend upward in the arrangement direction of the wafers 200. Each of the rod-shaped electrodes 269 d and 270 d is installed in parallel with the nozzle 233 d. Each of the rod-shaped electrodes 269 d and 270 d is protected by being covered by an electrode protection tube 275 d from above to below. One of the rod-shaped electrodes 269 d and 270 d is connected to the high frequency power supply 273 via the matching device 272, and the other is connected to the ground which is the reference potential. Here, the rod-shaped electrode 269 d is connected to the high frequency power supply 273 via the matching device 272, and the rod-shaped electrode 270 d is connected to the ground which is the reference potential. By applying an RF power between the rod-shaped electrodes 269 d and 270 d from the high frequency power supply 273 via the matching device 272, plasma is generated in a plasma generation region 224 d between the rod-shaped electrodes 269 d and 270 d.

A plasma excitation part (activation mechanism) that excites (activates) a gas into a plasma state mainly includes the rod-shaped electrodes 269 c and 270 c, the electrode protection tube 275 c, the rod-shaped electrodes 269 d and 270 d and the electrode protection tube 275 d. The matching device 272 and the high frequency power supply 273 may be included in the plasma excitation part. Further, the buffer chambers 237 c and 237 d may be included in the excitation part. The plasma excitation part including the rod-shaped electrodes 269 c and 270 c is also referred to as a first plasma excitation part. The plasma excitation part including the rod-shaped electrodes 269 d and 270 d is also referred to as a second plasma excitation part.

The exhaust port 231 a is installed below the side wall of the reaction tube 203. The exhaust pipe 231 configured to exhaust an internal atmosphere of the process chamber 201 is connected to the exhaust port 231 a. A vacuum pump 246 as a vacuum exhaust device is connected to the exhaust pipe 231 via a pressure sensor 245 serving as a pressure detector (pressure detecting part) configured to detect the internal pressure of the process chamber 201 and an APC (Auto Pressure Controller) valve 244 serving as a pressure regulator (pressure regulating part). The APC valve 244 is configured to perform or stop a vacuum exhausting operation in the process chamber 201 by opening/closing the valve while the vacuum pump 246 is actuated, and is also configured to be capable of adjusting the internal pressure of the process chamber 201 by adjusting an opening degree of the valve based on pressure information detected by the pressure sensor 245 while the vacuum pump 246 is actuated. An exhaust system mainly includes the exhaust pipe 231, the APC valve 244 and the pressure sensor 245. The exhaust system may include the vacuum pump 246.

A seal cap 219, which serves as a furnace opening cover configured to be capable of hermetically sealing a lower end opening of the reaction tube 203, is installed under the reaction tube 203. The seal cap 219 is made of, for example, a metal material such as stainless steel (SUS) or the like, and is formed in a disc shape. An O-ring 220, which is a seal member making contact with the lower end of the reaction tube 203, is installed at an upper surface of the seal cap 219.

A rotation mechanism 267 configured to rotate a boat 217, which will be described later, is installed under the seal cap 219. A rotary shaft 255 of the rotation mechanism 267 is connected to the boat 217 through the seal cap 219. The rotation mechanism 267 is configured to rotate the wafers 200 by rotating the boat 217. As shown in FIG. 2 , the rotation mechanism 267 rotates the wafers 200 in the direction of an arrow 200 r (counterclockwise). That is, when a predetermined position of an edge portion of the wafer 200 passes through a triangular region connecting the nozzles 233 a and 233 b and the center of the wafers 200 in the plane view, the rotation mechanism 267 rotates the wafers 200 so that the predetermined position passes through a straight line (first straight line) connecting the nozzle 233 a and the center of the wafers 200 and then passes through a straight line (second straight line) connecting the nozzle 233 b and the center of the wafers 200.

The seal cap 219 is configured to be vertically moved up or down by a boat elevator 115 as an elevating mechanism installed vertically outside the reaction tube 203. The boat elevator 115 is configured as a transfer device (transfer mechanism) that loads/unloads (transfers) the wafers 200 supported by the boat 217 in/from the process chamber 201 by moving the seal cap 219 up or down. That is, the boat elevator 115 is configured as a transfer device (transfer mechanism) that transfers the boat 217, that is, the wafers 200, in/out of the process chamber 201.

The boat 217 serving as a substrate support is configured to support a plurality of wafers 200, for example, 25 to 200 wafers, in such a state that the wafers 200 are arranged in a horizontal posture and in multiple stages along a vertical direction with the centers of the wafers 200 aligned with one another. That is, the boat 217 is configured to arrange the wafers 200 to be spaced apart from each other. The boat 217 is made of a heat resistant material such as quartz or SiC. Heat insulating plates 218 made of a heat resistant material such as quartz or SiC are held in multiple stages below the boat 217.

A temperature sensor 263 serving as a temperature detector is installed in the reaction tube 203. Based on temperature information detected by the temperature sensor 263, a state of supplying electric power to the heater 207 is adjusted such that an interior of the process chamber 201 has a desired temperature distribution. The temperature sensor 263 is in an L-shape, like the nozzle 233 a, and is installed along the inner wall of the reaction tube 203.

As shown in FIG. 3 , a controller 121, which is a control part (control means), may be configured as a computer including a central processing unit (CPU) 121 a, a random access memory (RAM) 121 b, a memory device 121 c and an I/O port 121 d. The RAM 121 b, the memory device 121 c and the I/O port 121 d are configured to be capable of exchanging data with the CPU 121 a via an internal bus 121 e. An input/output device 122 includes, for example, a touch panel or the like, is connected to the controller 121.

The memory device 121 c includes, for example, a flash memory, a hard disk drive (HDD) or the like. A control program for controlling operations of a substrate processing apparatus, a process recipe in which sequences, conditions, and the like of film formation to be described later are written, and the like are readably stored in the memory device 121 c. The process recipe functions as a program for causing the controller 121 to execute each sequence in the film formation, which will be described later, to obtain a predetermined result. Hereinafter, the process recipe, the control program and the like may be generally and simply referred to as a “program.” Furthermore, the process recipe may be simply referred to as a “recipe.” When the term “program” is used herein, it may indicate a case of including the recipe only, a case of including the control program only, or a case of including both the recipe and the control program. The RAM 121 b is configured as a memory area (work area) in which a program or data read by the CPU 121 a is temporarily stored.

The I/O port 121 d is connected to the MFCs 241 a 1 to 241 a 3, 241 b 1 to 241 b 3, 241 c 1, 241 c 2, 241 d 1 and 241 d 2, the valves 243 a 1 to 243 a 6, 243 b 1 to 243 b 6, 243 c 1 to 243 c 4 and 243 d 1 to 243 d 4, the pressure sensor 245, the APC valve 244, the vacuum pump 246, the heater 207, the temperature sensor 263, the rotation mechanism 267, the boat elevator 115, the high frequency power supply 273, the matching device 272 and so on.

The CPU 121 a is configured to read and execute the control program from the memory device 121 c. The CPU 121 a is further configured to read the recipe from the memory device 121 c according to an input of an operation command from the input/output device 122. In addition, the CPU 121 a is configured to control the flow rate adjusting operation of various kinds of gases by the MFCs 241 a 1 to 241 a 3, 241 b 1 to 241 b 3, 241 c 1, 241 c 2, 241 d 1 and 241 d 2, the opening/closing operation of the valves 243 a 1 to 243 a 6, 243 b 1 to 243 b 6, 243 c 1 to 243 c 4 and 243 d 1 to 243 d 4, the opening/closing operation of the APC valve 244, the pressure adjusting operation performed by the APC valve 244 based on the pressure sensor 245, the actuating and stopping of the vacuum pump 246, the temperature adjusting operation performed by the heater 207 based on the temperature sensor 263, the operation of rotating the boat 217 with the rotation mechanism 267 and adjusting the rotation speed of the boat 217, the operation of moving the boat 217 up or down by the boat elevator 115, the impedance adjusting operation by the matching device 272, the supply of power to the high frequency power supply 273 and so on, according to contents of the read recipe.

The controller 121 may be configured by installing, on the computer, the aforementioned program stored in an external memory device 123. The external memory device 123 includes, for example, a magnetic disk such as an HDD, an optical disc such as a CD, a magneto-optical disc such as an MO, or a semiconductor memory such as a USB memory. The memory device 121 c or the external memory device 123 is configured as a computer-readable recording medium. Hereinafter, the memory device 121 c and/or the external memory device 123 may be generally and simply referred to as a “recording medium.” When the term “recording medium” is used herein, it may indicate a case of including the memory device 121 c, a case of including the external memory device 123, or a case of including both the memory device 121 c and the external memory device 123. Furthermore, the program may be provided to the computer using communication means such as the Internet or a dedicated line, instead of using the external memory device 123.

(2) Substrate Processing Process

As one of processes of manufacturing a semiconductor device using the above-described substrate processing apparatus, an example of a substrate processing sequence of forming a nitride film, which is an insulating film, as a thin film, on a wafer 200 as a substrate, that is, a film-forming sequence, will be described. In the following descriptions, the operations of the respective parts constituting the substrate processing apparatus are controlled by the controller 121.

The film-forming sequence shown in FIG. 4 includes forming a silicon nitride film (SiN film) as a film on a wafer 200 in a process chamber 201 by performing a cycle a predetermined number of times, the cycle including non-simultaneously performing: (a) supplying a DCS gas as a precursor gas and an N₂ gas as an inert gas to the wafer 200; and (b) supplying an NH₃ gas as a reaction gas to the wafer 200, wherein in (a), at least one selected from the group of the DCS gas and the N₂ gas stored in a first tank 242 a 1 is supplied to the wafer 200 from a first nozzle 233 a as a first supply part (or a first supplier), and at least one selected from the group of the DCS gas and the N₂ gas stored in a second first tank 242 b 1 different from the first tank 242 a 1 is supplied to the wafer 200 from a second nozzle 233 b as a second supply part (or a second supplier) different from the first supply part, and wherein a concentration of DCS gas in the first tank 242 a 1 in a state where at least one selected from the group of the DCS gas and the N₂ gas is stored in the first tank 242 a 1 is set to be different from a concentration of DCS gas in the second tank 242 b 1 in a state where at least one selected from the group of the DCS gas and the N₂ gas is stored in the second tank 242 b 1.

In addition, FIG. 4 shows an example where the concentration of DCS gas in the first tank 242 a 1 in a state where at least one selected from the group of the DCS gas and the N₂ gas is stored in the first tank 242 a 1 is set to be higher than the concentration of DCS gas in the second tank 242 b 1 in a state where at least one selected from the group of the DCS gas and the N₂ gas is stored in the second tank 242 b 1, that is, the concentration of N₂ gas in the second tank 242 b 1 in the state where at least one selected from the group of the DCS gas and the N₂ gas is stored in the second tank 242 b 1 is set to be higher than the concentration of N₂ gas in the first tank 242 a 1 in the state where at least one selected from the group of the DCS gas and the N₂ gas is stored in the first tank 242 a 1.

Specifically, FIG. 4 shows an example where the concentration of DCS gas in the first tank 242 a 1 in the state where at least one selected from the group of the DCS gas and the N₂ gas is stored in the first tank 242 a 1 is set to 100% (the concentration of N₂ gas is 0%), and the concentration of DCS gas in the second tank 242 b 1 in the state where at least one selected from the group of the DCS gas and the N2 gas is stored in the second tank 242 b 1 is set to 0% (the concentration of N₂ gas is 100%).

Further, FIG. 4 shows an example where in (b), the NH₃ gas is plasma-excited and supplied to the wafer 200, that is, the NH₃ gas is plasma-excited and supplied as excited species such as NH₃*, that is, active species. More specifically, FIG. 4 shows an example where in (b), NH₃ gases supplied to a plurality of plasma excitation parts (or plasma exciters) at the same flow rate are respectively plasma-excited and supplied to the wafer 200, that is, active species such as NH₃* generated by respectively plasma-exciting NH₃ gases supplied to the plurality of plasma excitation parts at the same flow rate are supplied to the wafer 200 from the plurality of plasma excitation parts. For the sake of convenience, some of the supply timings of the N₂ gas are not shown in FIG. 4 . The same applies to FIGS. 5 and 6 to be described later.

In the present disclosure, the film-forming sequence shown in FIG. 4 may be expressed as follows for the sake of convenience. The same notation will be used in the description of other aspects and the like below. (DCS+N₂→NH₃*)×n⇒SiN

When the term “wafer” is used in the present disclosure, it may refer to “a wafer itself” or “a wafer and a laminated body of certain layers or films formed on a surface of the wafer.” When the phrase “a surface of a wafer” is used in the present disclosure, it may refer to “a surface of a wafer itself” or “a surface of a certain layer and the like formed on a wafer”. When the expression “a certain layer is formed on a wafer” is used in the present disclosure, it may mean that “a certain layer is formed directly on a surface of a wafer itself” or that “a certain layer is formed on a layer and the like formed on a wafer.” When the term “substrate” is used in the present disclosure, it may be synonymous with the term “wafer.”

(Wafer Charging and Boat Loading)

When a plurality of wafers 200 are charged into the boat 217 (wafer charging), as shown in FIG. 1 , the boat 217 supporting the plurality of wafers 200 is lifted by the boat elevator 115 and is loaded into the process chamber 201 (boat loading). In this state, the seal cap 219 seals the lower end of the reaction tube 203 via the O-ring 220.

(Pressure Adjustment and Temperature Adjustment)

The interior of the process chamber 201, that is, a space where the wafers 200 are placed, is vacuum-exhausted (decompression-exhausted) by the vacuum pump 246 to reach a desired pressure (degree of vacuum). At this time, the internal pressure of the process chamber 201 is measured by the pressure sensor 245, and the APC valve 244 is feedback-controlled based on the measured pressure information (pressure adjustment). Further, the wafers 200 in the process chamber 201 are heated by the heater 207 to a desired processing temperature. At this time, the supply of power to the heater 207 is feedback-controlled based on the temperature information detected by the temperature sensor 263 so that the interior of the process chamber 201 has a desired temperature distribution (temperature adjustment). Further, the rotation of the wafers 200 by the rotation mechanism 267 is started. The actuation of the vacuum pump 246, and the heating and rotation of the wafers 200 are continuously performed at least until the processing on the wafers 200 is completed.

(Pre-Purge 1)

Next, with the APC valve 244 fully opened, that is, with the interior of the process chamber 201 vacuum-exhausted, the valves 243 a 1, 243 b 1, 243 c 1, 243 c 3, 243 d 1 and 243 d 3 are closed, the valves 243 a 2 to 243 a 6, 243 b 2 to 243 b 6, 243 c 2, 243 c 4, 243 d 2 and 243 d 4 are opened, and a N₂ gas flows into the gas supply pipes 232 a 1, 232 b 1, 232 c 1 and 232 d 1. The flow rate of the N₂ gas is adjusted by the MFCs 241 a 2, 241 a 3, 241 b 2, 241 b 3, 241 c 2 and 241 d 2, and the N₂ gas is supplied into the process chamber 201 via the nozzles 233 a, 233 b, 233 c and 233 d and the buffer chambers 237 c and 237 d and is exhausted through the exhaust port 231 a. At this time, the supply flow rate of the N₂ gas supplied from each gas supply pipe is set to a predetermined flow rate in a range of, for example, 100 to 10,000 sccm, and the internal pressure of the process chamber 201 is set to a predetermined pressure in a range of, for example, 20 to 30 Pa. Thus, the interior of each of the supply system, the process chamber 201 and the exhaust system can be purged so that an environment and a state before the supply of the DCS gas inside these can be adjusted and aligned.

(Pre-Vacuum)

Thereafter, the valves 243 a 2, 243 a 3, 243 a 6, 243 b 2, 243 b 3, 243 b 6, 243 c 2, 243 c 4, 243 d 2 and 243 d 4 are closed while maintaining the state where the interior of the process chamber 201 is vacuum-exhausted, the valves 243 a 1, 243 b 1, 243 c 1, 243 c 3, 243 d 1 and 243 d 3 are closed, and the valves 243 a 4, 243 a 5, 243 b 4 and 243 b 5 are opened, whereby the supply of N₂ gas from each gas supply pipe is stopped, and the interior of each of the tanks 242 a 1 and 242 b 1 is vacuum-evacuated to a high vacuum state. At this time, the internal pressure of the process chamber 201 is set to a predetermined pressure within a range of, for example, 1 to 10 Pa. Thereafter, the valves 243 a 4, 243 a 5, 243 b 4 and 243 b 5 before and after (at the upstream side and the downstream side of) each of the tanks 242 a 1 and 242 b 1 are closed, and the interiors of the tanks 242 a 1 and 242 b 1 are respectively brought into a high-vacuum sealed state.

(Pre-Purge 2)

Thereafter, while maintaining the state where the interior of the process chamber 201 is vacuum-exhausted and the state where the interiors of the tanks 242 a 1 and 242 b 1 are in a high-vacuum sealed state, the valves 243 a 3, 243 a 6, 243 b 3, 243 b 6, 243 c 2, 243 c 4, 243 d 2 and 243 d 4 are opened, and the N₂ gas flows into the gas supply pipes 232 a 1, 232 b 1, 232 c 1 and 232 d 1. The flow rate of N₂ gas is adjusted by the MFCs 241 a 3, 241 b 3, 241 c 2 and 241 d 2, and the N₂ gas is supplied into the process chamber 201 via the nozzles 233 a, 233 b, 233 c and 233 d and the buffer chambers 237 c and 237 d and is exhausted through the exhaust port 231 a. Processing conditions at this time are the same as those in the above-described pre-purge 1. Thus, the interior of each of the supply system, the process chamber 201 and the exhaust system can be further purged so that the environment and the state before the supply of the DCS gas inside these can be further adjusted and aligned.

(Gas Charging into Tank)

Thereafter, with the valve 243 a 5 closed, the valves 243 a 1 and 243 a 4 are opened, and a DCS gas is flown into the gas supply pipe 232 a 1. The flow rate of DCS gas is adjusted by the MFC 241 a 1, and the DCS gas is supplied into the tank 242 a 1 and is stored in the tank 242 a 1. After the DCS gas is stored in the tank 242 a 1 at a predetermined pressure and predetermined amount, the valves 243 a 1 and 243 a 4 are closed, and the DCS gas is sealed (confined) in the tank 242 a 1. A volume of the tank 242 a 1 may be, for example, 300 to 500 cc in some embodiments. In this case, the internal pressure of the tank 242 a 1 when the DCS gas is sealed in the tank 242 a 1 may be set to a high pressure of, for example, 20,000 Pa or more in some embodiments, and the amount of DCS gas stored in the tank 242 a 1 may be set to, for example, 120 to 360 cc, specially 120 to 240 cc in some embodiments. Through a series of these operations, the operation of charging the DCS gas into the tank 242 a 1 is completed (gas charging into the first tank).

In addition, with the valve 243 b 5 closed, the valves 243 b 2 and 243 b 4 are opened, and the N₂ gas is flown into the gas supply pipe 232 b 1. The flow rate of N₂ gas is adjusted by the MFC 241 b 2, and the N₂ gas is supplied into the tank 242 b 1 and is stored in the tank 242 b 1. After a predetermined pressure and predetermined amount of N₂ gas is stored in the tank 242 b 1, the valves 243 b 2 and 243 b 4 are closed, and the N₂ gas is sealed (confined) in the tank 242 b 1. A volume of the tank 242 b 1 may be, for example, 300 to 500 cc in some embodiments. In this case, the internal pressure of the tank 242 b 1 when the N₂ gas is sealed in the tank 242 b 1 may be set to a high pressure of, for example, 20,000 Pa or more, and the amount of N₂ gas stored in the tank 242 b 1 may be set to, for example, 120 to 400 cc, specially 120 to 300 cc in some embodiments. Through a series of these operations, the operation of charging the N₂ gas into the tank 242 b 1 is completed (gas charging into the second tank).

At this time, the concentration of DCS gas stored in the tank 242 a 1 is set to be higher than the concentration of DCS gas stored in the tank 242 b 1. Further, the concentration of N₂ gas stored in the tank 242 b 1 is set to be higher than the concentration of N₂ gas stored in the tank 242 a 1. Further, the concentration of DCS gas stored in the tank 242 a 1 is set to be higher than the concentration of N₂ gas stored in the tank 242 a 1, and the concentration of N₂ gas stored in the tank 242 b 1 is set to be higher than the concentration of DCS gas stored in the tank 242 b 1. FIG. 4 shows an example where the concentration of DCS gas stored in the tank 242 a 1 is 100% (the concentration of N₂ gas is 0%), and the concentration of N₂ gas stored in the tank 242 b 1 is 100% (the concentration of DCS gas is 0%). For example, as shown in FIG. 5 , the concentration of DCS gas stored in the tank 242 a 1 may be set to 100% (the concentration of N₂ gas is 0%), and the concentration of N₂ gas stored in the tank 242 b 1 may be set to 90% (the concentration of DCS gas is 10%).

At this time, the amount of DCS gas stored in the tank 242 a 1 is set to be larger than the amount of DCS gas stored in the tank 242 b 1. Further, the amount of N₂ gas stored in the tank 242 b 1 is set to be larger than the amount of N₂ gas stored in the tank 242 a 1. Further, the amount of DCS gas stored in the tank 242 a 1 is set to be larger than the amount of N₂ gas stored in the tank 242 a 1, and the amount of N₂ gas stored in the tank 242 b 1 is larger than the amount of DCS gas stored in the tank 242 b 1. FIG. 4 shows an example where the DCS gas is stored (present) alone in the tank 242 a 1 with the amount of N₂ gas stored in the tank 242 a 1 set to 0 cc, and the N₂ gas is stored (present) alone in the tank 242 b 1 with the amount of DCS gas stored in the tank 242 b 1 set to 0 cc.

(N₂ Gas Charging into Process Chamber)

After the gas charging into the tank is completed, in the same manner as the above-described pre-purge 2, while the valves 243 a 3, 243 a 6, 243 b 3, 243 b 6, 243 c 2, 243 c 4, 243 d 2 and 243 d 4 are opened to maintain the state in which the N₂ gas is flown into the gas supply pipes 232 a 1, 232 b 1, 232 c 1 and 232 d 1, the APC valve 244 is fully closed to stop the exhaust of the interior of the process chamber 201. Thus, the interior of the process chamber 201 can be filled with the N₂ gas, and accordingly the internal pressure of the process chamber 201 can be increased. At this time, the supply flow rate of N₂ gas supplied from each gas supply pipe is set to a predetermined flow rate within a range of, for example, 100 to 10,000 sccm. Further, the internal pressure of the process chamber 201 is increased from a predetermined pressure in a range of, for example, 20 to 30 Pa to a predetermined pressure in a range of, for example, 200 to 400 Pa. Thus, when the DCS gas is supplied to the wafers 200 in the process chamber 201, diffusion of the DCS gas to the entire area in the process chamber 201 can be suppressed, and directionality (directivity) of DCS gas flow can be obtained. These operations make it possible to adjust the environment and state in the process chamber 201 before the supply of the DCS gas.

The above-described pre-purge 1, pre-vacuum, pre-purge 2, gas charging into the tank, and N₂ gas charging into the process chamber are preliminary preparations for performing a flash flow of DCS gas and N₂ gas to be described later.

(Film-Forming Step)

Thereafter, the following two steps, that is, steps A and B, are sequentially performed. [Step A]

In this step, the DCS gas stored in the first tank 242 a 1 and the N₂ gas stored in the second tank 242 b 1 are simultaneously supplied to the wafers 200 in the process chamber 201 from the first nozzle 233 a and the second nozzle 233 b, respectively.

After the interior of the process chamber 201 is filled with the N₂ gas so that the internal pressure of the process chamber 201 reaches a predetermined pressure, the valves 243 a 5 and 243 b 5 are opened while maintaining the state where the APC valve 244 is fully closed and the state where the valves 243 a 4 and 243 b 4 are closed. Thus, the high pressure DCS gas stored in the tank 242 a 1 is supplied at once (pulse-wise) into the process chamber 201 via the gas supply pipe 232 a 1 and the nozzle 233 a, and at the same time, the high pressure N₂ gas stored in the tank 242 b 1 is supplied at once (pulse-wise) into the process chamber 201 via the gas supply pipe 232 b 1 and the nozzle 233 b. Hereinafter, this supply method is referred to as a flash flow. At this time, since the APC valve 244 is closed, the internal pressure of the process chamber 201 rises rapidly to a predetermined pressure. Thereafter, the state in which the internal pressure of the process chamber 201 has risen is maintained for a predetermined time, and the wafer 200 is exposed to a high pressure DCS gas and N₂ gas atmosphere.

Processing conditions in this step are exemplified as follows:

-   -   Processing temperature: 250 to 650 degrees C., specifically 300         to 600 degrees C.     -   Processing pressure (before flash flow): 200 to 400 Pa     -   Processing pressure (after flash flow): 900 to 1,500 Pa     -   DCS gas supply amount (R1): 120 to 360 cc, specifically 120 to         240 cc     -   N₂ gas supply amount (R2): 120 to 400 cc, specifically 120 to         300 cc     -   N₂ gas supply flow rate (R3): 100 to 10,000 sccm     -   N₂ gas supply flow rate (R4): 100 to 10,000 sccm     -   DCS gas and N₂ gas exposure time: 1 to 20 seconds, specifically         5 to 10 seconds

In the present disclosure, notation of a numerical range such as “250 to 650 degrees C.” means that a lower limit value and an upper limit value are included in the range. For example, “250 to 650 degrees C.” means “equal to or higher than 250 degrees C. and equal to or lower than 650 degrees C.” The same applies to other numerical ranges.

By exposing the wafer 200 to the DCS gas and N₂ gas atmosphere under the above-described conditions, a Si-containing layer containing Cl is formed as a first layer on the outermost surface of the wafer 200. The Si-containing layer containing Cl is formed on the outermost surface of the wafer 200 by chemisorption or physisorption of DCS, chemisorption of a substance (hereinafter, SiH_(x)Cl_(y)) obtained by partially decomposing DCS, deposition of Si by thermal decomposition of DCS, and the like. The Si-containing layer containing Cl may be an adsorption layer (physisorption layer or chemisorption layer) of DCS or SiH_(x)Cl_(y), or may be a Si deposition layer containing Cl. In the present disclosure, the Si-containing layer containing Cl is also simply referred to as a Si-containing layer.

The concentration of DCS gas in the gas supplied by the flash flow through the nozzle 233 a is higher than the concentration of DCS gas in the gas supplied by the flash flow through the nozzle 233 b. Further, the concentration of N₂ gas in the gas supplied by the flash flow through the nozzle 233 b is higher than the concentration of N₂ gas in the gas supplied by the flash flow through the nozzle 233 a. Further, the concentration of DCS gas in the gas supplied by the flash flow through the nozzle 233 a is higher than the concentration of N₂ gas in the gas supplied by the flash flow through the nozzle 233 a, and the concentration of N₂ gas in the gas supplied by the flash flow through the nozzle 233 b is higher than the concentration of DCS gas in the gas supplied by the flash flow through the nozzle 233 b. FIG. 4 shows an example where the concentration of DCS gas in the gas supplied by the flash flow through the nozzle 233 a is set to 100% (the concentration of N₂ gas is 0%), and the concentration of N₂ gas in the gas supplied by the flash flow through the nozzle 233 b is set to 100% (the concentration of DCS gas is 0%). As shown in FIG. 5 , the concentration of DCS gas in the gas supplied by the flash flow through the nozzle 233 a may be set to 100% (the concentration of N₂ gas is 0%), and the concentration of N₂ gas in the gas supplied by the flash flow through the nozzle 233 b may be set to 90% (the concentration of DCS gas is 10%).

At this time, the amount of DCS gas in the gas supplied by the flash flow through the nozzle 233 a is larger than the amount of DCS gas in the gas supplied by the flash flow through the nozzle 233 b. Further, the amount of N₂ gas in the gas supplied by the flash flow through the nozzle 233 b is larger than the amount of N₂ gas in the gas supplied by the flash flow through the nozzle 233 a. Further, the amount of DCS gas in the gas supplied by the flash flow through the nozzle 233 a is larger than the amount of N₂ gas in the gas supplied by the flash flow through the nozzle 233 a, and the amount of N₂ gas in the gas supplied by the flash flow through the nozzle 233 b is larger than the amount of DCS gas in the gas supplied by the flash flow through the nozzle 233 b. FIG. 4 shows an example where the amount of N₂ gas supplied by the flash flow through the nozzle 233 a is 0 cc and the DCS gas is supplied alone by the flash flow through the nozzle 233 a, and the amount of DCS gas supplied by the flash flow through the nozzle 233 b is 0 cc and the N₂ gas is supplied alone by the flash flow through the nozzle 233 b.

In this manner, the concentrations of the DCS gas and the N₂ gas in the gas supplied by the flash flow through the nozzle 233 a are different from the concentrations of the DCS gas and the N₂ gas in the gas supplied by the flash flow through the nozzle 233 b, and the amounts of the DCS gas and the N₂ gas in the gas supplied by the flash flow through the nozzle 233 a are different from the amounts of the DCS gas and the N₂ gas in the gas supplied by the flash flow through the nozzle 233 b, whereby it is possible to suppress multiple adsorption of DCS molecules constituting the DCS gas on the outermost surface of the wafer 200. As a result, uniformity of the wafer in-plane film thickness of the SiN film formed on the wafer 200 can be improved. Further, it is possible to improve a film quality itself in addition to improving uniformity of a wafer in-plane film quality.

Multiple adsorption means that some DCS molecules are superimposed and adsorbed on the outermost surface of the wafer 200. In the present disclosure, when a thickness of a second layer (to be described later) formed per cycle is 1.4 to 2 Å or more, it is considered that multiple adsorption occurs, and when the thickness is 1.4 to 2 Å or less, it is considered that non-multiple adsorption occurs. For example, when the thickness of the second layer (to be described later) formed per cycle is 2.1 to 5 Å, it is considered that the multiple adsorption occurs, and when the thickness is 0.1 to 1.3 Å, it is considered that the non-multiple adsorption occurs. When the thickness of the second layer (to be described later) formed per cycle is 1.4 to 2 Å, it can be considered that the multiple adsorption occurs, it can be considered that the non-multiple adsorption occurs, or it can be considered that both adsorption states occur depending on the conditions. When the thickness of the second layer (to be described later) formed per cycle is less than 1.4 Å, it can be considered that the non-multiple adsorption occurs surely.

After the first layer is formed on the wafer 200, the APC valve 244, which has been fully closed, is fully opened to vacuum-exhaust the interior of the process chamber 201 to remove the gas remaining in the process chamber 201 from the process chamber 201 (purge 1). Processing procedure and processing conditions at this time can be the same as those in the above-described pre-purge 1. In purge 1, pre-purge 1, pre-vacuum and pre-purge 2 are performed for flash flow of the DCS gas and the N₂ gas in the next cycle.

As the precursor gas, in addition to the DCS gas, it may be possible to use a chlorosilane-based gas such as a monochlorosilane (SiH₃Cl, abbreviation: MCS) gas, a trichlorosilane (SiHCl₃, abbreviation: TCS) gas, a tetrachlorosilane (SiCl₄, abbreviation: STC) gas, a hexachlorodisilane (Si₂Cl₆, abbreviation: HCDS) gas, an octachlorotrisilane (Si₃Cl₈, abbreviation: OCTS) gas or the like, a bromosilane-based gas such as a tetrabromosilane (SiBr₄) gas or the like, an iodosilane-based gas such as a tetraiodosilane (SiI₄) gas, and an aminosilane-based gas such as a tetrakisdimethylaminosilane (Si[N(CH₃)₂]₄, abbreviation: 4DMAS) gas, a trisdimethylaminosilane (Si[N(CH₃)₂]₃H, abbreviation: 3DMAS) gas, a bisdiethylaminosilane (Si[N(C₂H₅)₂]₂H₂, abbreviation: BDEAS) gas, a bistertiarybutylaminosilane (SiH₂[NH(C₄H₉)]₂, abbreviation: BTBAS) gas, an diisopropylaminosilane (SiH₃[N(C₃H₇)₂], abbreviation: DIPAS) gas or the like. As the inert gas, in addition to the N₂ gas, it may be possible to use, for example, various rare gases such as an Ar gas, a He gas, a Ne gas, a Xe gas and the like. The same applies to step B to be described later.

[Step B]

In this step, an NH₃ gas is supplied to the wafer 200 in the process chamber 201, that is, the first layer (Si-containing layer) formed on the surface of the wafer 200. When supplying the NH₃ gas, the NH₃ gas is supplied to two plasma excitation parts at the same flow rate and is simultaneously plasma-excited in the two plasma excitation parts to generate active species such as NH₃*. The active species are simultaneously supplied from the two plasma excitation parts to the wafer 200 in the process chamber 201.

Specifically, with the APC valve 244 opened, that is, with the interior of the process chamber 201 exhausted, the valves 243 c 1 and 243 d 1 and the valves 243 c 3 and 243 d 3 are opened, and the NH₃ gas is flown into the gas supply pipes 232 c 1 and 232 d 1. The flow rate of NH₃ gas is adjusted by the MFCs 241 c 1 and 241 d 1, and the NH₃ gas is supplied into the process chamber 201 via the nozzles 233 c and 233 d and the buffer chambers 237 c and 237 d and is exhausted through the exhaust port 231 a (NH₃ gas pre-flow).

After performing the NH₃ gas pre-flow for a predetermined time, in a state where the supply of NH₃ gas into the process chamber 201 via the nozzles 233 c and 233 d and the buffer chambers 237 c and 237 d from the gas supply pipes 232 c 1 and 232 d 1 and the exhaust of NH₃ gas from the exhaust port 231 a are maintained, RF power is applied between the rod-shaped electrodes 269 c and 270 c and between the rod-shaped electrodes 269 d and 270 d. Thus, the NH₃ gas is plasma-excited in the buffer chambers 237 c and 237 d to generate the active species such as NH₃*, and the generated active species are simultaneously supplied to the wafer 200 from each of the buffer chambers 237 c and 237 d (NH₃* flow).

Processing conditions in this step are exemplified as follows:

-   -   Processing temperature: 250 to 650 degrees C., specifically 300         to 600 degrees C.     -   Processing pressure: 1 to 100 Pa, specifically 1 to 50 Pa     -   N₂ gas supply flow rate (R1): 100 to 10,000 sccm     -   N₂ gas supply flow rate (R2): 100 to 10,000 sccm     -   NH₃ gas supply flow rate (R3): 10 to 10,000 sccm     -   NH₃ gas supply flow rate (R4): 10 to 10,000 sccm     -   NH₃ gas pre-flow time: 1 to 10 seconds, specifically 1 to 5         seconds     -   NH₃* flow time: 1 to 60 seconds, specifically 5 to 30 seconds     -   High frequency power: 50 to 1,000 W

By supplying the NH₃ gas or the NH₃* to the wafer 200 under the above-described conditions, at least a portion of the first layer formed on the surface of the wafer 200 in step A is nitrided (modified). By nitriding the first layer, a layer containing Si and N, that is, a silicon nitride layer (SiN layer), is formed as the second layer on the surface of the wafer 200. The surface of the second layer is terminated with NH by being nitrided by the NH₃ gas or the NH₃*. When the second layer is formed, impurities such as Cl contained in the first layer forms a gaseous substance containing at least Cl in a process of nitridation reaction (modifying reaction) of the first layer by the NH₃ gas or the NH₃* and is discharged from the process chamber 201. Thus, the second layer becomes a layer having the impurities such as Cl fewer than those of the first layer formed in step A.

After the second layer is formed on the wafer 200, the valves 243 c 1 and 243 d 1 and the valves 243 c 3 and 243 d 3 are closed, and the application of RF power between the rod-shaped electrodes 269 c and 270 c and between the rod-shaped electrodes 269 d and 270 d is stopped so that the supply of NH₃ gas or NH₃* into the process chamber 201 is stopped. Then, the gas and the like remaining in the process chamber 201 are removed from the process chamber 201 according to the processing procedure and processing conditions which are the same as those of the purge 1 in step A (purge 2).

As the reaction gas, in addition to the NH₃ gas, it may be possible to use a hydrogen-nitride-based gas such as a diazene (N₂H₂) gas, a hydrazine (N₂H₄) gas, an N₃H₈ gas or the like.

The pre-purge 1, pre-vacuum and pre-purge 2 for the flush flow of the DCS gas and the N₂ gas in the next cycle are performed in the purge 1 as described above, but the gas charging into the tank for the flush flow of the DCS gas and the N₂ gas in the next cycle is performed in parallel with the NH₃ gas pre-flow and the NH₃* flow. FIG. 4 shows an example where the gas charging into the tank is performed in parallel with the NH₃* flow. Further, the N₂ gas charging into the process chamber for the flush flow of the DCS gas and the N₂ gas in the next cycle may be performed after the purge 2 or in the purge 2. As a result, the pre-purge 1, the pre-vacuum, the pre-purge 2, the gas charging into the tank, and the N₂ gas charging into the process chamber need not be separately performed in the next cycle, so that a cycle time can be shortened and a throughput can be improved.

[Performing Predetermined Number of Times]

A cycle that non-simultaneously, that is, alternately without synchronization, performs the above-described steps A and B is performed a predetermined number of times (n times, n being an integer of 1 or more) to thereby form a SiN film on the surface of the wafer 200. This cycle may be repeated multiple times. That is, the thickness of the SiN layer formed per cycle may be set to be smaller than a desired film thickness. Thus, the above-mentioned cycle may be repeated multiple times until the film thickness of a SiN film formed by laminating the SiN layers becomes equal to the desired film thickness.

(After-Purge and Returning to Atmospheric Pressure)

After the film-forming step is completed, the N₂ gas as the purge gas is supplied into the process chamber 201 from each of the gas supply pipes 232 a 1, 232 b 1, 232 c 1 and 232 d 1 and is exhausted through the exhaust port 231 a. Thus, the interior of the process chamber 201 is purged and the residual gas and the reaction byproducts remaining in the process chamber 201 are removed from the interior of the process chamber 201 (after-purge). Thereafter, the internal atmosphere of the process chamber 201 is substituted with the inert gas (inert gas substitution) and the internal pressure of the process chamber 201 is returned to the atmospheric pressure (returning to atmospheric pressure).

(Boat Unloading and Wafer Discharging)

Thereafter, the seal cap 219 is moved down by the boat elevator 115 to open the lower end of the reaction tube 203. Then, the processed wafers 200 supported by the boat 217 are unloaded from the lower end of the reaction tube 203 to the outside of the reaction tube 203 (boat unloading). Thereafter, the processed wafers 200 are discharged from the boat 217 (wafer discharging).

(3) Effects of the Present Embodiment

According to the present embodiment, one or more effects set forth below may be achieved.

(a) In the present embodiment, in step A, by supplying at least one selected from the group of the DCS gas and the N₂ gas stored in the tank 242 a 1 to the wafer 200 from the nozzle 233 a and supplying at least one selected from the group of the DCS gas and the N₂ gas stored in the tank 242 b 1 to the wafer 200 from the nozzle 233 b, the concentration of DCS gas in the tank 242 a 1 in the state where at least one selected from the group of the DCS gas and the N₂ gas is stored in the tank 242 a 1 is different from the concentration of DCS gas in the tank 242 b 1 in the state where at least one selected from the group of the DCS gas and the N₂ gas is stored in the tank 242 b 1. Thus, the concentration of DCS gas in the gas supplied by the flash flow through the nozzle 233 a can be different from the concentration of DCS gas in the gas supplied by the flash flow through the nozzle 233 b. That is, gases having different DCS gas concentrations can collide with each other and be brought into contact (mixed) in the plane of the wafer 200 by flash flow supply, so that multiple adsorption of DCS molecules constituting the DCS gas on the outermost surface of the wafer 200 can be suppressed and non-multiple adsorption can be promoted.

As a result, it is possible to improve the uniformity of the wafer in-plane thickness of the first layer formed on the wafer 200. As a result, it is possible to improve the uniformity of the wafer in-plane film thickness of the SiN film formed on the wafer 200. Further, since the uniformity of the wafer in-plane thickness of the first layer can be improved, the nitriding of the first layer in step B can be uniformly performed over the entire surface of the wafer, thereby improving the uniformity of the wafer in-plane film quality. Furthermore, since the multiple adsorption of DCS molecules can be suppressed, that is, the non-multiple adsorption can be promoted, not only the uniformity of the wafer in-plane thickness of the first layer can be improved, but also the thickness of the first layer can be reduced, and the nitriding of the first layer in step B can be uniformly and sufficiently performed over the entire surface of the wafer. This makes it possible to improve the film quality itself of the SiN film formed on the wafer 200. The film quality used here refers to, for example, wet etching resistance (HF resistance) of a film. In this case, improving the film quality means lowering the wet etching rate (hereinafter, referred to as WER) of the film to increase the wet etching resistance of the film.

In addition, when the concentration of DCS gas in the tank 242 a 1 in the state where at least one selected from the group of the DCS gas and the N₂ gas is stored in the tank 242 a 1 is set to be higher than the concentration of DCS gas in the tank 242 b 1 in the state where at least one of the DCS gas and the N₂ gas is stored in the tank 242 b 1 and when the concentration of N₂ gas in the tank 242 b 1 in the state where at least one selected from the group of the DCS gas and the N₂ gas is stored in the tank 242 b 1 is set to be higher than the concentration of N₂ gas in the tank 242 a 1 in the state where at least one selected from the group of the DCS gas and the N₂ gas is stored in the tank 242 a 1, it is possible to increase the above-described effect of suppressing the multiple adsorption of DCS molecules (the effect of promoting the non-multiple adsorption).

In addition, when the concentration of DCS gas in the tank 242 a 1 in the state where at least one selected from the group of the DCS gas and the N₂ gas is stored in the tank 242 a 1 is set to be higher than the concentration of N₂ gas in the tank 242 a 1 and when the concentration of N₂ gas in the tank 242 b 1 in the state where at least one selected from the group of the DCS gas and the N₂ gas is stored in the tank 242 b 1 is set to be higher than the concentration of DCS gas in the tank 242 b 1, it is possible to increase the above-described effect of suppressing the multiple adsorption of DCS molecules.

In addition, when the amount of DCS gas in the tank 242 a 1 in the state where at least one selected from the group of the DCS gas and the N₂ gas is stored in the tank 242 a 1 is set to be larger than the amount of DCS gas in the tank 242 b 1 in the state where at least one selected from the group of the DCS gas and the N₂ gas is stored in the tank 242 b 1 and when the amount of N₂ gas in the tank 242 b 1 in the state where at least one selected from the group of the DCS gas and the N₂ gas is stored in the tank 242 b 1 is set to be larger than the amount of N₂ gas in the tank 242 a 1 in the state where at least one selected from the group of the DCS gas and the N₂ gas is stored in the tank 242 a 1, it is possible to increase the above-described effect of suppressing the multiple adsorption of DCS molecules.

In addition, when the amount of DCS gas in the tank 242 a 1 in the state where at least one selected from the group of the DCS gas and the N₂ gas is stored in the tank 242 a 1 is set to be larger than the amount of N₂ gas in the tank 242 a 1 and when the amount of N₂ gas in the tank 242 b 1 in the state where at least one selected from the group of the DCS gas and the N₂ gas is stored in the tank 242 b 1 is set to be larger than the amount of DCS gas in the tank 242 b 1, it is possible to increase the above-described effect of suppressing the multiple adsorption of DCS molecules.

In particular, when the concentration of DCS gas in the tank 242 a 1 in the state where at least one selected from the group of the DCS gas and the N₂ gas is stored in the tank 242 a 1 is set to 100% (the concentration of N₂ gas is set to 0%) and when the concentration of N₂ gas in the tank 242 b 1 in the state where at least one selected from the group of the DCS gas and the N₂ gas is stored in the tank 242 b 1 is set to 100% (the concentration of DCS gas is set to 0%), in step A, since the DCS gas of the concentration of 100% supplied by the flash flow and the N₂ gas of the concentration of 100% supplied by the flash flow can collide with each other and be brought into contact (mixing) in the plane of the wafer 200, it is possible to further increase the above-described effect of suppressing the multiple adsorption of DCS molecules.

That is, when the DCS gas is present alone in the tank 242 a 1 in the state where at least one selected from the group of the DCS gas and the N₂ gas is stored in the tank 242 a 1 and when the N₂ gas is present alone in the tank 242 b 1 in the state where at least one selected from the group of the DCS gas and the N₂ gas is stored in the tank 242 b 1, it is possible to further increase the above-described effect of suppressing the multiple adsorption of DCS molecules.

(b) In performing at least step A, when a predetermined position of the edge portion of the wafers 200 passes through a triangular region connecting the nozzles 233 a and 233 b and the center of the wafers 200 in the plane view, by rotating the wafers 200 such that the predetermined position passes through the straight line (first straight line) connecting the nozzle 233 a and the center of the wafer 200 and then passes through the straight line (second straight line) connecting the nozzle 233 b and the center of the wafer 200 (in the direction of the arrow 200 r shown in FIG. 2 ), a predetermined area in the plane of the wafer exposed to the DCS gas by supplying the DCS gas by the flash flow from the nozzle 233 a can be promptly exposed to the N₂ gas supplied by the flash flow from the nozzle 233 b, thereby further increasing the above-described effect of suppressing the multiple adsorption of DCS molecules.

In addition, this effect is not limited to the case where the DCS gas is supplied alone by the flash flow from the nozzle 233 a and the N₂ gas is supplied alone by the flash flow from the nozzle 233 b as shown in FIG. 4 , but may be obtained even a case where the DCS gas is supplied alone by the flash flow from the nozzle 233 a and a mixed gas of the N₂ gas and the DCS gas is supplied by the flash flow from the nozzle 233 b as shown in FIG. 5 . In addition, this effect may be obtained even a case where a mixed gas of the N₂ gas and the DCS gas is supplied by the flash flow from each of the nozzles 233 a and 233 b. However, in any case, the concentration (amount) of DCS gas in the gas supplied by the flash flow from the nozzle 233 a needs to be set to be higher (larger) than the concentration (amount) of DCS gas in the gas supplied by the flash flow from the nozzle 233 b, and the concentration (amount) of N₂ gas in the gas supplied by the flash flow from the nozzle 233 b needs to be set to be higher (larger) than the concentration (amount) of N₂ gas in the gas supplied by the flash flow from the nozzle 233 a.

(c) Before at least one selected from the group of the DCS gas and the N₂ gas is supplied by the flash flow from each of the nozzles 233 a and 233 b in step A, by filling the interior of the process chamber 201 with the N₂ gas to increase the internal pressure of the process chamber 201, it is possible to suppress the diffusion of the DCS gas to the entire area in the process chamber 201 when the DCS gas is supplied to the wafer 200 in the process chamber 201 and obtain the directionality (directivity) of the DCS gas flow. This makes it possible to further enhance the above-described effect of suppressing multiple adsorption of DCS molecules by causing gases having different DCS gas concentrations to collide with each other and be brought into contact (mixed) in the plane of the wafer 200 by flash flow supply.

(d) Before at least one selected from the group of the DCS gas and the N₂ gas is supplied by the flash flow from each of the nozzles 233 a and 233 b in step A, when the interior of the process chamber 201 is filled with the N₂ gas, by fully closing the APC valve 244 to stop the exhaust of the interior of the process chamber 201, it is possible to efficiently increase the internal pressure of the process chamber 201, thereby efficiently and sufficiently obtaining the above-described effect.

(e) When supplying at least one selected from the group of the DCS gas and the N₂ gas by the flash flow from each of the nozzles 233 a and 233 b in step A, by maintaining the state in which the internal pressure of the process chamber 201 is increased, it is possible to suppress the diffusion of the DCS gas to the entire area in the process chamber 201 when the DCS gas is supplied to the wafer 200 in the process chamber 201 and obtain the directionality (directivity) of the DCS gas flow. This makes it possible to further enhance the above-described effect of suppressing multiple adsorption of DCS molecules by causing gases having different DCS gas concentrations to collide with each other and be brought into contact (mixing) in the plane of the wafer 200 by flash flow supply.

(f) When supplying at least one selected from the group of the DCS gas and the N₂ gas by the flash flow from each of the nozzles 233 a and 233 b in step A, by fully closing the APC valve 244 to stop the exhaust of the interior of the process chamber 201, it is easy to maintain the state where the internal pressure of the process chamber 201 is increased, thereby efficiently and sufficiently obtaining the above-described effect.

(g) When at least one selected from the group of the DCS gas and the N₂ gas is supplied by the flash flow from each of the nozzles 233 a and 233 b in step A, by setting the concentration of DCS gas in the tank 242 a 1 in the state where at least one selected from the group of the DCS gas and the N₂ gas is stored in the tank 242 a 1 to be different from the concentration of DCS gas in the tank 242 b 1 in the state where at least one selected from the group of the DCS gas and the N₂ gas is stored in the tank 242 b 1, it is possible to reduce the use amount of DCS gas as compared to a case where the DCS gas of the same concentration is stored in the tanks 242 a 1 and 242 b 1, thereby reducing a precursor gas cost.

(h) Since the use amount of DCS gas can be reduced, the flow rate of the diluted N₂ gas flown into the exhaust pipe 231 at the downstream side of the vacuum pump 246 can be reduced in order to comply with the standard of the explosion limit of DCS gas, thereby significantly reducing the use amount of the N₂ gas and hence significantly reducing an N₂ gas cost. The explosion limit of DCS gas refers to the concentration of 4.1 to 99% of the explosion range in the atmosphere indicated in a safety data sheet of the chemical substance DCS. According to the safety data sheet, the concentration of DCS gas in the exhaust pipe at the downstream side of the vacuum pump must not exceed 4.1%, but this is a rule that focuses on safety. This means that when an unintended disaster such as an earthquake causes an external leak (mixture with the atmosphere) in the exhaust pipe at the downstream side of the vacuum pump, an explosion will not occur if the concentration of DCS gas in the exhaust pipe does not exceed 4.1%. This is a minimum standard for ensuring device safety just in case.

(i) Since the use amount of DCS gas can be reduced, a period during which the amount of generated particles can be kept low can be extended, thereby lengthening a maintenance cycle and significantly reducing a device operation costs.

(j) The above-described effects resulting from the reduction in the use amount of DCS gas are remarkable when a difference between the concentration of DCS gas in the tank 242 a 1 and the concentration of DCS gas in the tank 242 b 1 is large, particularly more remarkable when the concentration of DCS gas in the tank 242 a 1 in the state where at least one selected from the group of the DCS gas and the N₂ gas is stored in the tank 242 a 1 is set to 100% (the concentration of the N₂ gas is 0%) and when the concentration of N₂ gas in the tank 242 b 1 in the state where at least one selected from the group of the DCS gas and the N₂ gas is stored in the tank 242 b 1 is set to 100% (the concentration of the DCS gas is 0%).

(k) The SiN film formed in the above-described embodiments has high film thickness uniformity, high film quality uniformity, low chlorine concentration in the film, and high film quality, that is, high etching resistance. Therefore, the SiN film formed in the above-described embodiments can be suitably used as a sidewall spacer, an etching stopper, a hard mask and the like in various semiconductor devices such as a logic device, a memory device and the like.

Other Embodiments of the Present Disclosure

While some embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the above-described embodiments but may be variously modified without departing from the subject matter of the present disclosure.

The example in which the NH₃ gases supplied to the plurality of plasma excitation parts at the same flow rate are respectively plasma-excited and supplied to the wafer 200 in step B has been described in the above-described embodiments. However, the present disclosure is not limited to such embodiments. For example, as shown in FIG. 6 , in step B, the NH₃ gases supplied at different flow rates to the plurality of plasma excitation parts may be respectively plasma-excited and supplied to the wafer 200. That is, in step B, active species such as NH₃* generated by respectively plasma-exciting the NH₃ gases supplied to the plurality of plasma excitation parts at different flow rates may be supplied to the wafer 200 from the plurality of plasma excitation parts. In this case, the NH₃ gas supply flow rate (R3) may be, for example, 1,000 to 3,000 sccm, and the NH₃ gas supply flow rate (R4) may be, for example, 2,000 to 5,000 sccm. Other processing conditions may be the same as the processing conditions in the above-described embodiments.

In this case, since the amount of NH₃ gas or NH₃* supplied from the buffer chambers 237 c and 237 d can be set to be different from each other, a nitridation amount of the first layer in the plane of the wafer 200 can be adjusted. This makes it possible to improve the uniformity of wafer in-plane film quality of the SiN film formed on the wafer 200, and it is also possible to improve the film quality itself of the SiN film formed on the wafer 200, depending on a method of adjusting the nitridation amount in the plane of the wafer 200.

In addition, the example in which the two buffer chambers 237 c and 237 d are arranged so as to face each other with the center of the wafer 200 interposed therebetween has been described in the above-described embodiments. However, the present disclosure is not limited to such embodiments. For example, the two buffer chambers 237 c and 237 d may be arranged in the line-symmetrical relationship, with having a straight line connecting the center of the wafer 200, that is, the center of the reaction tube 203, and the center of the exhaust port 231 a as a symmetrical axis in the plane view, may be respectively arranged so as to be closer to the exhaust port 231 a side, or may be arranged so as to be closer to the side distant from the exhaust port 231 a. In other words, a central angle formed by a straight line connecting the center of the buffer chamber 237 c and the center of the wafer 200 and a straight line connecting the center of the buffer chamber 237 d and the center of the wafer 200 (a central angle with respect to an arc with centers of the buffer chambers 237 c and 237 d as both ends) is not limited to 180°, and may be less than 180° or excess 180°. In any of these cases, the gas supply holes 250 c and 250 d of the buffer chambers 237 c and 237 d are formed in the line-symmetrical relationship with having the straight line connecting the center of the wafer 200 and the center of the exhaust port 231 a as the symmetrical axis. Even in these cases, the same effects as those in the above-described embodiments can be obtained.

In addition, the example in which the two plasma excitation parts are installed has been described in the above-described embodiments. However, three or more plasma excitation parts may be installed. Even in such a case, the plurality of plasma excitation parts may be installed in the line-symmetrical relationship with having the straight line connecting the center of the wafer 200 and the center of the exhaust port 231 a as the symmetrical axis in the plane view. Even in these cases, the same effects as those in the above-described embodiments can be obtained.

In addition, the examples in which the SiN film is formed as the thin film by using the DCS gas as the precursor gas and the NH₃ gas as the reaction gas have been described in the above-described embodiments. However, the present disclosure is not limited to such an embodiment.

For example, as the precursor gas, in addition to the above-described halosilane-based gas such as the DCS gas and aminosilane-based gas, it may be possible to use a metal halide gas such as a titanium tetrachloride (TiCl₄) gas or the like. Further, for example, as the reaction gas, in addition to the N-containing gas such as the NH₃ gas, it may be possible to use an oxygen (O)-containing gas such as an oxygen (O₂) gas, an N and carbon (C)-containing gas such as a triethylamine ((C₂H₅)₃N, abbreviation: TEA) gas, a C-containing gas such as a propylene (C₃H₆) gas, a boron (B)-containing gas such as a trichloroborane (BCl₃) gas, and the like. Then, according to the following gas supply sequence, a silicon oxynitride film (SiON film), a silicon carbonitride film (SiCN film), a silicon oxycarbonitride film (SiOCN film), a silicon oxycarbide film (SiOC film), a silicon oxide film (SiO film), a silicon boronitride film (SiBN film), a silicon borocarbonitride film (SiBCN film), a titanium nitride film (TiN film), a titanium oxynitride film (TiON film) or the like may be formed on the surface of the wafer 200. Even in these cases, the same effects as those in the above-described embodiments can be obtained. (DCS+N₂→NH₃*→O₂)×n⇒SiON (DCS+N₂→C₃H₆→NH₃*)×n⇒SiCN (DCS+N₂→C₃H₆→NH₃*→O₂)×n⇒SiOCN (DCS+N₂→TEA→NH₃*→O₂)×n⇒SiOC(N) (BDEAS+N₂→O₂*)×n⇒SiO (DCS+N₂→BCl₃→NH₃*)×n⇒SiBN (DCS+N₂→C₃H₆→BCl₃→NH₃*)×n⇒SiBCN (TiCl₄+N₂→NH₃*)×n⇒TiN (TiCl₄+N₂→NH₃*→O₂)×n⇒TiON

In this manner, the present disclosure may be applied not only to formation of a silicon-containing film such as the SiN film and the SiON film, but also to formation of a metal-containing film such as the TiN film, and even in such cases, the same effects as those in the above-described embodiments may be achieved. That is, the present disclosure may be applied to a case where a film containing a predetermined element such as a metalloid element (semiconductor element) or a metal element is formed.

Recipes used in each process may be provided individually according to the processing contents and may be stored in the memory device 121 c via a telecommunication line or the external memory device 123 in some embodiments. Moreover, when each process begins, the CPU 121 a may properly select an appropriate recipe from the recipes stored in the memory device 121 c according to the processing contents in some embodiments. Thus, it is possible for a single substrate processing apparatus to form films of various kinds, composition ratios, qualities, and thicknesses with enhanced reproducibility. Further, it is possible to reduce an operator's burden and to quickly start each substrate processing while avoiding an operation error.

The recipes mentioned above are not limited to newly-provided ones but may be provided, for example, by modifying existing recipes that are already installed in the substrate processing apparatus. Once the recipes are modified, the modified recipes may be installed in the substrate processing apparatus via a telecommunication line or a recording medium storing the recipes. In addition, the existing recipes already installed in the existing substrate processing apparatus may be directly modified by operating the input/output device 122 of the substrate processing apparatus.

The examples in which films are formed using a batch-type substrate processing apparatus capable of processing a plurality of substrates at a time have been described in the above-described embodiments. The present disclosure is not limited to the above-described embodiments but may be suitably applied, for example, to a case where films are formed using a single-wafer-type substrate processing apparatus capable of processing a single substrate or several substrates at a time. In addition, the examples in which films are formed using a substrate processing apparatus including a hot-wall-type process furnace have been described in the above-described embodiments. The present disclosure is not limited to the above-described embodiments but may be suitably applied to a case where films are formed using a substrate processing apparatus including a cold-wall-type process furnace.

Even in the case of using these substrate processing apparatuses, each process may be performed according to the same processing procedures and processing conditions as those in the above-described embodiments, and the same effects as those of the above-described embodiments can be achieved.

The above-described embodiments may be used in proper combination. The processing procedures and processing conditions used in such cases may be the same as those of the above-described embodiments.

EXAMPLES Example 1

The substrate processing apparatus shown in FIG. 1 is used to form SiN films on a plurality of wafers according to a film-forming sequence in the same as or similar to the film-forming sequence in the above-described embodiments. In the gas charging into the tank, the amount of each gas stored in each tank is set under the following three conditions (conditions 1 to 3), and evaluation samples of three types of SiN films were provided. Processing conditions other than the gas charging into the tank are the same as the processing conditions in the above-described embodiments, and are the same in the conditions 1 to 3.

<Condition 1>

Amount of DCS gas stored in a first tank: 200 to 300 cc

-   -   Amount of N₂ gas stored in the first tank: 0 cc     -   Amount of DCS gas stored in a second tank: 0 cc     -   Amount of N₂ gas stored in the second tank: 200 to 300 cc     -   Concentration of DCS gas stored in the first tank         (100%)>concentration of DCS gas stored in the second tank (0%)         <Condition 2>

Amount of DCS gas stored in the first tank: 200 to 300 cc

-   -   Amount of N₂ gas stored in the first tank: 0 cc     -   Amount of DCS gas stored in the second tank: 200 to 300 cc     -   Amount of N₂ gas stored in the second tank: 0 cc     -   Concentration of DCS gas stored in the first tank         (100%)=concentration of DCS gas stored in the second tank (100%)         <Condition 3>

Amount of DCS gas stored in the first tank: 100 to 150 cc

-   -   Amount of N₂ gas stored in the first tank: 100 to 150 cc     -   Amount of DCS gas stored in the second tank: 100 to 150 cc     -   Amount of N₂ gas stored in the second tank: 100 to 150 cc     -   Concentration of DCS gas stored in the first tank (40 to         60%)=concentration of DCS gas stored in the second tank (40 to         60%)

After the evaluation samples of three types of SiN films are provided, the uniformity of wafer in-plane film thickness and the uniformity of inter-wafer film thickness of each SiN film are measured. The results are shown in FIG. 7 . It can be seen that as the respective values of the uniformity of wafer in-plane film thickness and the uniformity of inter-wafer film thickness decrease, the uniformities becomes better (the uniformities increase).

It can be confirmed from FIG. 7 that the wafer in-plane film thickness uniformity and the inter-wafer film thickness uniformity of the SiN film formed under the condition 1 are respectively better than the wafer in-plane film thickness uniformity and the inter-wafer film thickness uniformity of the SiN film formed under the conditions 2 and 3.

Example 2

The substrate processing apparatus shown in FIG. 1 is used to form SiN films on a plurality of wafers according to a film-forming sequence in the same as or similar to the film-forming sequence in the above-described embodiments. In the gas charging into the tank, the amount of each gas stored in each tank is set under the two conditions 1 and 2 in Example 1, and evaluation samples of two types of SiN films are provided. The processing conditions other than the gas charging into the tank are the same as the processing conditions in the above-described embodiments, and are the same in the conditions 1 and 2.

After providing the evaluation samples of two types of SiN films, each SiN film is subjected to wet etching using a 1% HF aqueous solution, and the wet etching rate (WER) of each SiN film is measured. The results are shown in FIG. 8 .

A horizontal axis in FIG. 8 represents a boat zone, that is, a position of each wafer in to vertical direction of a boat when SiN films are formed on a plurality of wafers, in which T, CT, C, CB and B indicate a top, a center top, a center, a center bottom, and a bottom of the boat, respectively. The “Average” at the right end of the horizontal axis in FIG. 8 indicates averages of the values on a vertical axis in T, CT, C, CB and B. The vertical axis in FIG. 8 represents a ratio of WER (hereinafter referred as a WER ratio) when the average of WERs of the SiN films formed on the wafers disposed on each of T, CT, C, CB and B under the condition 2 is 1 (reference). It can be seen that as a value of the WER ratio decreases, a wet etching resistance increases.

It can be confirmed from FIG. 8 that the value of the WER ratio of the SiN film formed under the condition 1 is smaller than the value of the WER ratio of the SiN film formed under the condition 2, and the wet etching resistance of the SiN film formed under the condition 1 is higher than that of the SiN film formed under the condition 2. It can be also confirmed that the SiN film formed under the condition 1 have a good inter-wafer uniformity of the WER ratio.

Example 3

The substrate processing apparatus shown in FIG. 1 is used to form SiN films on a plurality of wafers according to a film-forming sequence in the same as or similar to the film-forming sequence in the above-described embodiments. In the gas charging into the tank, the amount of each gas stored in each tank is set under the two conditions 1 and 2 in Example 1, and samples of two types of SiN films are provided. The processing conditions other than the gas charging into the tank are the same as the processing conditions in the above-described embodiments, and are the same in the conditions 1 and 2.

At this time, an effective flow rate of DCS gas and the flow rate of diluted N₂ gas flown into the exhaust pipe at the downstream side of the vacuum pump in order to comply with the standard of the explosion limit of the DCS gas are measured. The results are shown in FIG. 9 .

It can be confirmed from FIG. 9 that the effective flow rate of DCS gas can be reduced and the flow rate of diluted N₂ gas flown into the exhaust pipe on the downstream side of the vacuum pump can be reduced in a case where the SiN film is formed under the condition 1 as compared with a case where the SiN film is formed under the condition 2. Further, it is confirmed that by forming the SiN film under the condition 1, the use amount of DCS gas and the use amount of N₂ gas can be reduced by 40%, respectively, as compared with a case where the SiN film is formed under the condition 2, and the use amounts of the gases can be significantly reduced, thereby significantly reducing a gas cost.

Example 4

The substrate processing apparatus shown in FIG. 1 is used to form SiN films on a plurality of wafers according to a film-forming sequence in the same as or similar to the film-forming sequence shown in FIG. 6 . In step B, the flow rate of NH₃ gas supplied into each buffer chamber is set under the following two conditions 4 and 5, and evaluation samples of two types of SiN films are provided. Other processing conditions are the same as the processing conditions in the above-described embodiments, and are the same in the conditions 4 and 5.

<Condition 4>

NH₃ gas flow rate supplied into a first buffer chamber: 1 to 2 slm

NH₃ gas flow rate supplied into a second buffer chamber: 5 to 6 slm

NH₃ gas flow rate supplied into the first buffer chamber<NH₃ gas flow rate supplied into the second buffer chamber

<Condition 5>

NH₃ gas flow rate supplied into the first buffer chamber: 3 to 4 slm

-   -   NH₃ gas flow rate supplied into the second buffer chamber: 3 to         4 slm     -   NH₃ gas flow rate supplied into the first buffer chamber=NH₃ gas         flow rate supplied into the second buffer chamber

After providing the evaluation samples of two types of SiN films, each SiN film is subjected to wet etching using a 1% HF aqueous solution, and a WER of each SiN film is measured. The results are shown in FIG. 10 . FIG. 10 shows a WER ratio when the WER of the SiN film formed on the wafer under the condition 5 is 1 (reference).

It can be confirmed from FIG. 10 that a value of the WER ratio of the SiN film formed under the condition 4 is smaller than a value of the WER ratio (reference value) of the SiN film formed under the condition 5, and a wet etching resistance of the SiN film formed under the condition 4 is higher than that of the SiN film formed under the condition 5.

According to the present disclosure in some embodiments, it is possible to improve uniformity of substrate in-plane film thickness of a film formed on a substrate.

While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosures. Indeed, the embodiments described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the disclosures. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosures. 

What is claimed is:
 1. A method of processing a substrate, comprising: forming a film on the substrate in a process chamber by performing a cycle a predetermined number of times, the cycle including non-simultaneously performing: (a) supplying a precursor gas and an inert gas to the substrate; and (b) supplying a reaction gas to the substrate, wherein in (a), at least one selected from the group of the precursor gas and the inert gas stored in a first tank is supplied to the substrate from a first supplier, and at least one selected from the group of the precursor gas and the inert gas stored in a second tank different from the first tank is supplied to the substrate from a second supplier different from the first supplier, wherein a concentration of the precursor gas in the first tank in a state where at least one selected from the group of the precursor gas and the inert gas is stored in the first tank is set to be different from a concentration of the precursor gas in the second tank in a state where at least one selected from the group of the precursor gas and the inert gas is stored in the second tank, and wherein in (a), the at least one selected from the group of the precursor gas and the inert gas supplied from the first supplier and the at least one selected from the group of the precursor gas and the inert gas supplied from the second supplier are in contact with each other in a plane of the substrate so as to suppress multiple adsorption of molecules constituting the precursor gas on a surface of the substrate.
 2. The method of claim 1, wherein the concentration of the precursor gas in the first tank in the state where at least one selected from the group of the precursor gas and the inert gas is stored in the first tank is set to be higher than the concentration of the precursor gas in the second tank in the state where at least one selected from the group of the precursor gas and the inert gas is stored in the second tank.
 3. The method of claim 1, wherein a concentration of the inert gas in the second tank in the state where at least one selected from the group of the precursor gas and the inert gas is stored in the second tank is set to be higher than a concentration of the inert gas in the first tank in the state where at least one selected from the group of the precursor gas and the inert gas is stored in the first tank.
 4. The method of claim 1, wherein the concentration of the precursor gas in the first tank is set to be higher than a concentration of the inert gas in the first tank in the state where at least one selected from the group of the precursor gas and the inert gas is stored in the first tank, and wherein a concentration of the inert gas in the second tank is set to be higher than the concentration of the precursor gas in the second tank in the state where at least one selected from the group of the precursor gas and the inert gas is stored in the second tank.
 5. The method of claim 1, wherein the concentration of the precursor gas in the first tank in the state where at least one selected from the group of the precursor gas and the inert gas is stored in the first tank is set to 100%, and wherein a concentration of the inert gas in the second tank in the state where at least one selected from the group of the precursor gas and the inert gas is stored in the second tank is set to 100%.
 6. The method of claim 1, wherein an amount of the precursor gas in the first tank in the state where at least one selected from the group of the precursor gas and the inert gas is stored in the first tank is set to be larger than an amount of the precursor gas in the second tank in the state where at least one selected from the group of the precursor gas and the inert gas is stored in the second tank.
 7. The method of claim 1, wherein an amount of the inert gas in the second tank in the state where at least one selected from the group of the precursor gas and the inert gas is stored in the second tank is set to be larger than an amount of the inert gas in the first tank in the state where at least one selected from the group of the precursor gas and the inert gas is stored in the first tank.
 8. The method of claim 1, wherein an amount of the precursor gas in the first tank is set to be larger than an amount of the inert gas in the first tank in the state where at least one selected from the group of the precursor gas and the inert gas is stored in the first tank, and wherein an amount of the inert gas in the second tank is set to be larger than an amount of the precursor gas in the second tank in the state where at least one selected from the group of the precursor gas and the inert gas is stored in the second tank.
 9. The method of claim 1, wherein the precursor gas is present alone in the first tank in the state where at least one selected from the group of the precursor gas and the inert gas is stored in the first tank, and wherein the inert gas is present alone in the second tank in the state where at least one selected from the group of the precursor gas and the inert gas is stored in the second tank.
 10. The method of claim 1, wherein a central angle formed by a first straight line connecting a center of the substrate and the first supplier and a second straight line connecting the center of the substrate and the second supplier in a plane view is an acute angle, and wherein in at least (a), when a predetermined position of an edge portion of the substrate passes through a triangular region connecting the first supplier, the second supplier, and the center of the substrate in the plane view, the substrate is rotated such that the predetermined position passes through the second straight line after passing through the first straight line.
 11. The method of claim 1, wherein in (a), the at least one selected from the group of the precursor gas and the inert gas supplied from the first supplier and the at least one selected from the group of the precursor gas and the inert gas supplied from the second supplier are mixed with each other in the plane of the substrate so as to promote non-multiple adsorption of molecules constituting the precursor gas on a surface of the substrate.
 12. The method of claim 1, wherein in (a), the precursor gas supplied from the first supplier and the inert gas supplied from the second supplier are in contact with each other in the plane of the substrate so as to suppress multiple adsorption of molecules constituting the precursor gas on a surface of the substrate.
 13. The method of claim 1, wherein in (a), the precursor gas supplied from the first supplier and the inert gas supplied from the second supplier are mixed with each other in the plane of the substrate so as to promote non-multiple adsorption of molecules constituting the precursor gas on a surface of the substrate.
 14. The method of claim 1, wherein (a) is performed in a state where an exhaust of the precursor gas from the process chamber is stopped.
 15. The method of claim 1, wherein (a) is performed in a state where a valve installed at an exhaust pipe configured to exhaust an interior of the process chamber is fully closed.
 16. The method of claim 1, wherein in (a), the process chamber is filled with the inert gas before the precursor gas and the inert gas are supplied to the substrate.
 17. The method of claim 1, wherein in (b), the reaction gas supplied to a plurality of plasma exciters at different flow rates is plasma-excited in each of the plurality of plasma exciters and supplied to the substrate.
 18. A method of manufacturing a semiconductor device comprising the method of claim
 1. 19. A substrate processing apparatus comprising: a process chamber in which a substrate is processed; a first supply system configured to supply at least one selected from the group of a precursor gas and an inert gas stored in a first tank to the substrate in the process chamber from a first supplier; a second supply system configured to supply at least one selected from the group of the precursor gas and the inert gas stored in a second tank different from the first tank to the substrate in the process chamber from a second supplier different from the first supplier; a third supply system configured to supply a reaction gas to the substrate in the process chamber; and a controller configured to be capable of controlling the first supply system, the second supply system and the third supply system to perform a process of forming a film on the substrate in the process chamber by performing a cycle a predetermined number of times, the cycle including non-simultaneously performing: (a) supplying the precursor gas and the inert gas to the substrate; and (b) supplying the reaction gas to the substrate, wherein in (a), at least one selected from the group of the precursor gas and the inert gas stored in the first tank is supplied to the substrate from the first supplier, and at least one selected from the group of the precursor gas and the inert gas stored in the second tank is supplied to the substrate from the second supplier, wherein a concentration of the precursor gas in the first tank in a state where at least one selected from the group of the precursor gas and the inert gas is stored in the first tank is set to be different from a concentration of the precursor gas in the second tank in a state where at least one selected from the group of the precursor gas and the inert gas is stored in the second tank, and wherein in (a), the at least one selected from the group of the precursor gas and the inert gas supplied from the first supplier and the at least one selected from the group of the precursor gas and the inert gas supplied from the second supplier are in contact with each other in a plane of the substrate so as to suppress multiple adsorption of molecules constituting the precursor gas on a surface of the substrate.
 20. A non-transitory computer-readable recording medium storing a program that causes, by a computer, a substrate processing apparatus to perform a process comprising: forming a film on a substrate in a process chamber of the substrate processing apparatus by performing a cycle a predetermined number of times, the cycle including non-simultaneously performing: (a) supplying a precursor gas and an inert gas to the substrate; and (b) supplying a reaction gas to the substrate, wherein in (a), at least one selected from the group of the precursor gas and the inert gas stored in a first tank is supplied to the substrate from a first supplier, and at least one selected from the group of the precursor gas and the inert gas stored in a second tank different from the first tank is supplied to the substrate from a second supplier different from the first supplier, wherein a concentration of the precursor gas in the first tank in a state where at least one selected from the group of the precursor gas and the inert gas is stored in the first tank is set to be different from a concentration of the precursor gas in the second tank in a state where at least one selected from the group of the precursor gas and the inert gas is stored in the second tank, and wherein in (a), the at least one selected from the group of the precursor gas and the inert gas supplied from the first supplier and the at least one selected from the group of the precursor gas and the inert gas supplied from the second supplier are in contact with each other in a plane of the substrate so as to suppress multiple adsorption of molecules constituting the precursor gas on a surface of the substrate. 